Preparation method of LDH intercalation composite graphene lubricating oil additive

Abstract

The invention belongs to the technical field of lubricating oil additives, and particularly relates to a preparation method of an LDH intercalation composite graphene lubricating oil additive. Zirconium oxychloride octahydrate and aluminum trichloride are used as raw materials, layered double hydroxide LDH is prepared to serve as a main body of the lubricating oil additive, meanwhile, powdery graphene is added, sedimentation of a graphene material is avoided by regulating and controlling the structure of the layered double hydroxide LDH and intercalation modification, and the friction performance of the lubricating oil additive is effectively improved.

Description

Technical Field

[0001] The invention belongs to the technical field of lubricating oil additives, and particularly relates to a method for preparing a LDH intercalated composite graphene lubricating oil additive. Background Art

[0002] Friction and wear are ubiquitous in everyday life and nature. They consume significant amounts of energy, causing mechanical transmission components to wear out and fail, shortening their service life. This leads to increasingly prominent problems such as energy consumption and mechanical losses. Lubricants can effectively reduce friction and wear, and suitable anti-friction and anti-wear additives are crucial components for improving lubricant performance. Therefore, the exploration and development of new, environmentally friendly lubricant additives has become a key research focus for researchers in the field of friction. Layered double hydroxides (LDHs) are an important class of two-dimensional layered materials with a unique structure and tunable chemical composition, making them suitable for use as lubricant additives. Graphene, with its excellent mechanical and thermal properties, ultrathin layered structure, and large surface area, can significantly reduce friction and wear. However, the large number of oxygen-containing functional groups on its surface makes graphene hydrophilic, making it difficult to stably disperse in lubricants.

[0003] A Chinese patent (publication number CN109777576B) discloses a graphene lubricant additive and its preparation method. This invention uses microwaves to exfoliate intercalated graphite in situ within a base oil to form graphene. Graphene oxide is then used to promote the dispersion of the exfoliated graphene sheets. The exfoliated graphene sheets are then stably dispersed in the base oil with the combined action of a detergent and a dispersant, resulting in a graphene lubricant additive. This avoids the problem of graphene agglomeration after preparation, simplifies the process, and significantly reduces energy consumption and pollution. The resulting graphene lubricant additive exhibits no agglomeration, excellent dispersibility, and superior wear reduction and anti-wear properties. However, existing techniques for ensuring the stable dispersion of graphene in lubricant additives without the addition of detergents and dispersants, and effectively improving friction performance when used in lubricants, remain unresolved.

[0004] Therefore, the present invention provides a method for preparing an LDH intercalated composite graphene lubricant additive, which uses layered double hydroxide (LDH) as the main body of the lubricant additive and regulates the structure and intercalation modification of the layered double hydroxide (LDH) to avoid the sedimentation of the graphene material, while effectively improving the friction performance of the lubricant additive. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a method for preparing an LDH intercalated composite graphene lubricant additive, aiming to ensure that the graphene is stably dispersed in the lubricant additive without adding detergents, dispersants, etc., without sedimentation, and effectively improve the friction performance when it is applied to lubricating oil.

[0006] The present invention uses zirconium oxychloride octahydrate and aluminum trichloride as raw materials to prepare layered double hydroxide (LDH) as the main body of the lubricating oil additive, and simultaneously adds powdered graphene. The structure and intercalation modification of the layered double hydroxide (LDH) are regulated to avoid the sedimentation of the graphene material, thereby effectively improving the friction performance of the lubricating oil additive.

[0007] The technical solutions adopted by the present invention to solve the above technical problems are as follows:

[0008] The present invention provides a method for preparing a LDH intercalated composite graphene lubricant additive, comprising the following steps:

[0009] S1: wet ball milling of commercially available graphene solution followed by vacuum freeze drying to obtain powdered graphene;

[0010] S2: preparing a precursor using the powdered graphene, zirconium oxychloride octahydrate and aluminum chloride;

[0011] S3: performing intercalation modification on the precursor to obtain an LDH intercalated composite graphene lubricant additive.

[0012] The present invention adds powdered graphene to the ZrAl-LDH during preparation for compounding, and uses sodium laurate to perform intercalation modification after forming a precursor, thereby obtaining an LDH intercalation composite graphene lubricating oil additive. On the one hand, LDH has a large specific surface area and edge structural defect sites (metal ions at the edge of LDH are exposed due to incomplete hydroxyl coordination and form unsaturated coordination). These characteristics promote the adsorption of the LDH material on the friction surface and form a protective coating on the surface, thereby improving the performance of the lubricating oil. On the other hand, by using sodium laurate to perform intercalation modification on the composite material, the dispersibility and tribological properties of the ZrAl-LDH / powdered graphene in oil can be further improved.

[0013] As a preferred technical solution of the present invention, the particle size D50 of the powdered graphene in step S1 is 3 to 6 μm, and the specific surface area is 750 to 850 m 2 / g.

[0014] As a preferred technical solution of the present invention, the particle size of the powdered graphene can be 3μm, 3.5μm, 4μm, 4.5μm, 5μm, 5.5μm or 6μm, etc.

[0015] As a preferred technical solution of the present invention, the specific surface area of ​​the powdered graphene can be 750m 2 / g、770m 2 / g、790m 2 / g、810m 2 / g、830m 2 / g or 850m 2 / g, etc.

[0016] As a preferred technical solution of the present invention, the wet ball milling step in step S1 includes: placing 40 to 50 parts of commercially available graphene solution and 80 to 100 parts of deionized water in a stainless steel barrel of a ball mill, using a tetrafluoroethylene frosted dispersion disk, then adding zirconium beads into the barrel, connecting and turning on condensation water, controlling the ball mill speed to 4000 to 4400 r / min and stirring for 4 to 6 hours, and filtering to obtain a filtrate.

[0017] As a preferred technical solution of the present invention, the weight proportions of the commercially available graphene solution may be 40 parts, 42 parts, 44 parts, 46 parts, 48 ​​parts or 50 parts, etc.

[0018] The graphene particles of powdered graphene can be dispersed to form a "bearing-like" structure, converting sliding friction into rolling friction, thereby reducing the friction coefficient and effectively improving the anti-wear performance; at the same time, by controlling the particle size of the powdered graphene within a suitable size range, the powdered graphene can more easily enter the LDH interlayer, forming a stable intercalation structure, thereby improving the stability of the lubricant additive; by controlling the specific surface area range of the powdered graphene, it is ensured that the powdered graphene and LDH have sufficient interaction sites, thereby enhancing the intercalation stability; at the same time, a good specific surface area can also promote the adsorption of friction pair particles in the lubricating oil between the LDH layers, thereby reducing the friction coefficient and the average wear scar diameter.

[0019] As a preferred technical solution of the present invention, the conditions for vacuum freeze-drying in step S1 include: vacuum degree of 10 to 12 Pa, temperature of -20 to -30°C, and time of 60 to 70 hours.

[0020] As a preferred technical solution of the present invention, the method for preparing the precursor in step S2 includes: dispersing 0.1 to 0.3 parts of the powdered graphene in 100 to 200 parts of deionized water to form a dispersion, dissolving 6 to 8 parts of zirconium oxychloride octahydrate and 0.6 to 0.8 parts of aluminum trichloride in 200 to 300 parts of deionized water to form liquid A, dissolving 12 to 15 parts of an auxiliary agent in 250 to 300 parts of deionized water to form liquid B, adding liquid A and liquid B to the dispersion for aging treatment to obtain a precursor.

[0021] Zirconium oxychloride octahydrate and aluminum chloride dissociate in water, where Zr 4+Easy to form multinuclear hydroxyl bridged complexes, Al 3+ Mononuclear species will be generated, and the two will be bridged to form a positively charged two-dimensional lamellar structure. At the same time, with the help of additives, co-precipitation is promoted and the generation of impurities is avoided, eventually forming an ordered LDH layered structure.

[0022] As a preferred technical solution of the present invention, the weight proportion of the powdered graphene can be 0.1 part, 0.15 part, 0.2 part, 0.25 part or 0.3 part, etc.

[0023] As a preferred technical solution of the present invention, the weight proportion of the zirconium oxychloride octahydrate can be 6 parts, 6.5 parts, 7 parts, 7.5 parts or 8 parts.

[0024] As a preferred technical solution of the present invention, the weight proportion of the aluminum chloride can be 0.6 parts, 0.65 parts, 0.7 parts, 0.75 parts or 0.8 parts, etc.

[0025] As a preferred technical solution of the present invention, the weight proportion of the auxiliary agent can be 12 parts, 12.5 parts, 13 parts, 13.5 parts, 14 parts, 14.5 parts or 15 parts.

[0026] As a preferred technical solution of the present invention, the aging treatment conditions include: controlling the pH to 9.8-10.2, aging at room temperature for 12-14 hours, filtering, washing with deionized water, and vacuum drying.

[0027] As a preferred technical solution of the present invention, the auxiliary agent is selected from one or more of sodium hydroxide, sodium carbonate, sodium bicarbonate, and sodium phosphate.

[0028] As a preferred technical solution of the present invention, the auxiliary agent is preferably sodium hydroxide and sodium carbonate.

[0029] As a preferred technical solution of the present invention, the mass ratio of sodium hydroxide to sodium carbonate in the auxiliary agent is (1.5-2.0):1; for example, it can be 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1 or 2.0:1.

[0030] Sodium hydroxide and sodium carbonate are selected as additives, and the mass ratio of sodium hydroxide to sodium carbonate is controlled to ensure a good compounding effect, which can improve the stability and friction performance of lubricating oil additives. Sodium hydroxide, as a strong base, can provide an alkaline environment and adjust the pH of the reaction system to a higher level, which is beneficial for Zr 4+ and Al 3+ Provides the necessary conditions for the hydrolysis of Zr 4+ and Al 3+After being activated, it can promote the generation of metal hydroxide precursors, providing a basis for the formation of layered structures; the carbonate ion of sodium carbonate can act as an interlayer anion and insert into the interlayer gaps of ZrAl-LDH to balance the positive charge on the layer plates. At the same time, the carbonate ion can also enhance the stability of the layered structure and prevent the layer plates from collapsing or disordered stacking; through the synergistic effect of sodium hydroxide and sodium carbonate, the stacking of the layer plates is guided, the formation of the layered structure is promoted, and finally ZrAl-LDH is obtained.

[0031] As a preferred technical solution of the present invention, the intercalation modification step includes: immersing the precursor in a 0.04-0.06 mol / L sodium laurate solution and stirring for 50-60 minutes, washing with deionized water, and drying.

[0032] Sodium laurate dissociates into laurate ions and sodium ions in aqueous solution. Laurate, as a larger organic anion, enters the LDH interlayer through ion exchange. The insertion of laurate significantly increases the interlayer spacing of LDH. At the same time, the negatively charged laurate and the positively charged layers are stably bound through electrostatic interaction. In addition, the flexibility of the long-chain alkyl group of sodium laurate allows the interlayer structure to be adjusted within a certain range, thereby being able to adapt to different environments to improve stability.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] (1) The present invention adds powdered graphene to the ZrAl-LDH during the preparation process for compounding, and uses sodium laurate to perform intercalation modification after forming a precursor, thereby obtaining an LDH intercalation composite graphene lubricant additive; on the one hand, LDH has a large specific surface area and unsaturated bonds, and these properties promote the adsorption of the LDH plate on the friction surface and form a protective coating on the surface, thereby improving the performance of the lubricant; on the other hand, by using sodium laurate to perform intercalation modification on the composite material, the dispersibility and tribological properties of ZrAl-LDH / powdered graphene in oil can be further improved.

[0035] (2) The powdered graphene in the lubricating oil additive of the present invention has low friction properties, and its two-dimensional layered structure is easy to slide under shear force, significantly reducing friction; the long-chain alkyl group of sodium laurate forms a physical adsorption film at the friction interface, reducing direct metal contact and achieving adsorption lubrication; the layered structure of ZrAl-LDH slides under shear force, further reducing friction through interlayer slippage; the synergistic effect of the three ensures that the lubricating oil additive has good stability, while reducing the friction coefficient and average wear scar diameter.

[0036] (3) The graphene particles of the powdered graphene of the present invention are dispersed to form a "bearing-like" structure through friction repair, which converts sliding friction into rolling friction, thereby reducing the friction coefficient and effectively improving the anti-wear performance; at the same time, by controlling the particle size of the powdered graphene within a suitable size range, the powdered graphene can more easily enter the LDH interlayer, forming a stable intercalation structure, thereby improving the stability of the lubricant additive; by controlling the specific surface area range of the powdered graphene, it is ensured that the powdered graphene and LDH have sufficient interaction sites, thereby enhancing the intercalation stability; at the same time, the good specific surface area can also promote the adsorption of friction pair particles in the lubricating oil between the LDH layers, thereby reducing the friction coefficient and the average wear scar diameter.

[0037] (4) The zirconium oxychloride octahydrate and aluminum chloride of the present invention dissociate in water, wherein Zr 4+ Easy to form multinuclear hydroxyl bridged complexes, Al 3+ Mononuclear species will be generated, and the two will be bridged to form a positively charged two-dimensional lamellar structure. At the same time, with the help of additives, co-precipitation is promoted and the generation of impurities is avoided, eventually forming an ordered LDH layered structure.

[0038] (5) The present invention uses sodium hydroxide and sodium carbonate as auxiliary agents. Sodium hydroxide, as a strong base, can provide an alkaline environment and adjust the pH of the reaction system to a higher level, which is beneficial for the 4+ and Al 3+ Provides the necessary conditions for the hydrolysis of Zr 4+ and Al 3+ After being activated, it can promote the generation of metal hydroxide precursors, providing a basis for the formation of layered structures; the carbonate ion of sodium carbonate can act as an interlayer anion and insert into the interlayer gaps of ZrAl-LDH to balance the positive charge on the layer plates. At the same time, the carbonate ion can also enhance the stability of the layered structure and prevent the layer plates from collapsing or disordered stacking; through the synergistic effect of sodium hydroxide and sodium carbonate, the stacking of the layer plates is guided, the formation of the layered structure is promoted, and finally ZrAl-LDH is obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0040] Figure 1 is the wear scar diameter of the friction performance test in Application Example 1.

[0041] Figure 2 The results of the stability test of Application Example 1 are shown in FIG.

[0042] Figure 3 is the wear scar diameter of the friction performance test in Application Example 9.

[0043] Figure 4 is the wear scar diameter of the friction performance test in Application Example 10.

[0044] Figure 5 The results of the stability test of Application Example 10 are shown. DETAILED DESCRIPTION

[0045] For the convenience of understanding the present invention, the present invention is given below with examples. It should be understood by those skilled in the art that the examples are only for the purpose of helping to understand the present invention and should not be regarded as specific limitations of the present invention.

[0046] The sources of some components in the Examples and Comparative Examples are as follows:

[0047] Graphene powder I, product number SE1331, particle size D50 is 5 μm, specific surface area is 15 m 2 / g, purchased from Changzhou Sixth Element Materials Technology Co., Ltd.;

[0048] Graphene powder II, product number SE1234, particle size D50 is 20 μm, specific surface area is 800 m 2 / g, purchased from Changzhou Sixth Element Materials Technology Co., Ltd.;

[0049] Commercially available graphene solution, product number G196548, was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0050] Zirconium oxychloride octahydrate, CAS No. 13520-92-8, was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0051] Aluminum trichloride, CAS No. 7446-70-0, was purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0052] Sodium hydroxide, CAS No. 1310-73-2, was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0053] Sodium carbonate, CAS No. 497-19-8, was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0054] Sodium laurate, CAS No. 629-25-4, was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0055] Example 1

[0056] This embodiment provides a method for preparing a LDH intercalated composite graphene lubricant additive, comprising the following steps:

[0057] S1: In parts by weight, 50 parts of commercially available graphene solution and 100 parts of deionized water were placed in a stainless steel barrel of a ball mill, a tetrafluoroethylene frosted dispersion disk was used, zirconium beads were added to the barrel, condensation water was connected and opened, the ball mill speed was controlled to 4400 r / min and stirred for 4 hours, the filtrate was filtered to obtain the filtrate, and then vacuum freeze-dried (vacuum degree of 12 Pa, temperature of -30 ° C, time of 60 hours) to obtain powdered graphene (particle size D50 of 6 μm, specific surface area of ​​750 m 2 / g);

[0058] S2: In parts by weight, 0.3 parts of the powdered graphene are dispersed in 200 parts of deionized water to form a dispersion, 8 parts of zirconium oxychloride octahydrate and 0.8 parts of aluminum chloride are dissolved in 300 parts of deionized water to form a solution A, and 15 parts of an auxiliary agent (9 parts of sodium hydroxide and 6 parts of sodium carbonate) are dissolved in 300 parts of deionized water to form a solution B. The solutions A and B are added to the dispersion for aging treatment, the pH is controlled to 10.2, and the mixture is aged at room temperature for 14 hours, filtered, washed with deionized water, and vacuum dried to obtain a precursor;

[0059] S3: Soaking the precursor in a 0.06 mol / L sodium laurate solution and stirring for 50 minutes, washing with deionized water, and drying to obtain an LDH intercalated composite graphene lubricant additive.

[0060] Example 2

[0061] This embodiment provides a method for preparing a LDH intercalated composite graphene lubricant additive, comprising the following steps:

[0062] S1: In parts by weight, 40 parts of commercially available graphene solution and 80 parts of deionized water were placed in a stainless steel barrel of a ball mill. A tetrafluoroethylene frosted dispersion disc was used, and zirconium beads were added to the barrel. The condenser was connected and opened, and the ball mill speed was controlled to 4000 r / min and stirred for 6 hours. The filtrate was filtered to obtain the filtrate, and then vacuum freeze-dried (vacuum degree of 10 Pa, temperature of -20 ° C, time of 70 hours) to obtain powdered graphene (particle size D50 of 3 μm, specific surface area of ​​850 m 2 / g);

[0063] S2: In parts by weight, 0.1 parts of the powdered graphene are dispersed in 100 parts of deionized water to form a dispersion, 6 parts of zirconium oxychloride octahydrate and 0.6 parts of aluminum chloride are dissolved in 200 parts of deionized water to form a solution A, and 12 parts of an auxiliary agent (8 parts of sodium hydroxide and 4 parts of sodium carbonate) are dissolved in 250 parts of deionized water to form a solution B. The solutions A and B are added to the dispersion for aging treatment, the pH is controlled to 9.8, and the mixture is aged at room temperature for 12 hours, filtered, washed with deionized water, and vacuum dried to obtain a precursor;

[0064] S3: Soaking the precursor in a 0.04 mol / L sodium laurate solution and stirring for 60 minutes, washing with deionized water, and drying to obtain an LDH intercalated composite graphene lubricant additive.

[0065] Example 3

[0066] This embodiment provides a method for preparing a LDH intercalated composite graphene lubricant additive, comprising the following steps:

[0067] S1: In parts by weight, 45 parts of commercially available graphene solution and 90 parts of deionized water were placed in a stainless steel barrel of a ball mill. A tetrafluoroethylene frosted dispersion disc was used, and zirconium beads were added to the barrel. The condenser water was connected and opened, and the ball mill speed was controlled to 4200 r / min and stirred for 5 h. The filtrate was filtered to obtain the filtrate, and then vacuum freeze-dried (vacuum degree of 11 Pa, temperature of -25 ° C, time of 66 h) to obtain powdered graphene (particle size D50 of 5 μm, specific surface area of ​​800 m 2 / g);

[0068] S2: In parts by weight, 0.2 parts of the powdered graphene are dispersed in 150 parts of deionized water to form a dispersion, 7 parts of zirconium oxychloride octahydrate and 0.7 parts of aluminum chloride are dissolved in 250 parts of deionized water to form a solution A, and 13 parts of an auxiliary agent (8 parts of sodium hydroxide and 5 parts of sodium carbonate) are dissolved in 280 parts of deionized water to form a solution B. Solutions A and B are added to the dispersion for aging treatment, the pH is controlled to 10, and the mixture is aged at room temperature for 13 hours. The mixture is filtered, washed with deionized water, and vacuum dried to obtain a precursor;

[0069] S3: Soaking the precursor in a 0.05 mol / L sodium laurate solution and stirring for 55 minutes, washing with deionized water, and drying to obtain an LDH intercalated composite graphene lubricant additive.

[0070] Comparative Example 1

[0071] The difference between this comparative example and Example 1 is that commercially available graphene powder I (article number SE1331, particle size D50 is 5 μm, specific surface area is 15 m 2 / g) to replace powdered graphene.

[0072] Comparative Example 2

[0073] The difference between this comparative example and Example 1 is that commercially available graphene powder II (article number SE1234, particle size D50 is 20 μm, specific surface area is 800 m 2 / g) to replace powdered graphene.

[0074] Comparative Example 3

[0075] The difference between this comparative example and Example 1 is that the amount of sodium hydroxide in the auxiliary agent is changed to 12 parts, and the amount of sodium carbonate is changed to 3 parts.

[0076] Comparative Example 4

[0077] The difference between this comparative example and Example 1 is that the amount of sodium hydroxide in the auxiliary agent is changed to 5 parts, and the amount of sodium carbonate is changed to 10 parts.

[0078] Comparative Example 5

[0079] The difference between this comparative example and Example 1 is that no sodium laurate solution is used for intercalation modification in step S3.

[0080] Preparation of the application example: 60 g of commercially available gear oil and 1 wt% of lubricating oil additive were placed in the stainless steel barrel of a ball mill. A tetrafluoroethylene frosted dispersion disk was used and zirconium beads were added to the barrel. After connection, condensation water was turned on, the ball mill was turned on, and the speed was gradually adjusted to 4000 r / min and stirred continuously for 6 hours. After the end, the lubricating oil was filtered using a sieve to obtain the lubricating oil.

[0081] The friction performance and stability of the lubricating oil provided in the above application example were tested. The specific test method is as follows:

[0082] (1) Friction performance test

[0083] With reference to "SH / T 0189-2017 Determination of Anti-wear Performance of Lubricating Oils - Four-Ball Method", the test was carried out using a four-ball tribometer. Three steel balls with a diameter of 12.7 mm were clamped in an oil box and covered with the above-mentioned lubricating oil. Another steel ball with a diameter of 12.7 mm was placed on top of the three balls and subjected to a force of 392 N, forming a "three-point contact". When the lubricating oil temperature reached 75°C, the top ball was rotated at a speed of 1200 r / min for 60 minutes. The wear spot diameters of the three lower steel balls were measured, and the average value of the wear spot diameters was taken as the average wear scar diameter. At the same time, the friction coefficient was calculated.

[0084] (2) Stability test

[0085] Take 20mL of lubricating oil and place it in a transparent colorless glass bottle for 3 months to observe whether there is any sedimentation to evaluate the stability of the lubricating oil.

[0086] The above performance test data is shown in Table 1.

[0087] Table 1 Performance test results

[0088]

[0089]

[0090] From the above content, it can be seen that the present invention adds powdered graphene for compounding during the preparation of ZrAl-LDH, and uses sodium laurate to perform intercalation modification after forming the precursor, thereby obtaining an LDH intercalated composite graphene lubricant additive, and mixing it with commercially available gear oil to obtain a lubricant with better comprehensive performance (Application Examples 1 to 3).

[0091] Compared with Example 1, commercially available graphene powder I (article number SE1331) was used instead of powdered graphene. Since the specific surface area of ​​commercially available graphene powder I was too small, the interaction sites with LDH were insufficient, and the intercalation stability was reduced, the friction performance of the lubricating oil deteriorated and the stability decreased (Application Example 4); Compared with Example 1, commercially available graphene powder II (article number SE1234) was used instead of powdered graphene. Since the particle size D50 of commercially available graphene powder II was too large, it was difficult to enter the LDH interlayer to form a stable intercalation structure, the friction performance of the lubricating oil deteriorated and the stability decreased (Application Example 5); Compared with Example 1, the amount of sodium hydroxide in the additive was changed to 12 parts, and the amount of sodium carbonate was changed to 3 parts. The number of carbonate ions was reduced, the stability of the layered structure deteriorated, and the layer collapse or disordered stacking was prone to occur. If the compounding effect is not good, the friction performance of the lubricating oil deteriorates and the stability decreases (Application Example 6); compared with Example 1, the amount of sodium hydroxide in the additive is changed to 5 parts, and the amount of sodium carbonate is changed to 10 parts. The hydrolysis of metal ions becomes weaker and the activity decreases, the amount of metal hydroxide precursors is reduced, the compounding effect is not good, the friction performance of the lubricating oil deteriorates, and the stability decreases (Application Example 7); compared with Example 1, sodium laurate solution is not used for intercalation modification in step S3, and the long-chain alkyl group of sodium laurate is lacking to form a physical adsorption film at the friction interface, so the friction performance of the lubricating oil deteriorates and the stability decreases (Application Example 8); compared with Application Example 1, gear oil is directly used as the lubricating oil. Due to the lack of the LDH intercalation composite graphene lubricating oil additive of the present invention, the friction performance deteriorates (Application Example 9), which can be seen in detail. Figure 3 Compared with Application Example 1, 0.1 wt% of powdered graphene was used to replace 1 wt% of the lubricant additive. Due to the poor dispersion of graphene, sedimentation occurred, resulting in instability of the lubricant system, which deteriorated the friction performance and decreased the stability (Application Example 10). For details, see Figure 4 and Figure 5 .

[0092] In summary, the present invention uses zirconium oxychloride octahydrate and aluminum trichloride as raw materials to prepare layered double hydroxide (LDH) as the main body of the lubricating oil additive, and simultaneously adds powdered graphene. By regulating the structure and intercalation modification of the layered double hydroxide (LDH), the sedimentation of the graphene material is avoided, thereby effectively improving the friction performance of the lubricating oil additive.

Claims

1. A method for preparing a LDH intercalated composite graphene lubricant additive, characterized in that: The following steps are involved: S1: wet ball milling of commercially available graphene solution followed by vacuum freeze drying to obtain powdered graphene; S2: preparing a precursor using the powdered graphene, zirconium oxychloride octahydrate and aluminum chloride; S3: performing intercalation modification on the precursor to obtain an LDH intercalated composite graphene lubricant additive.

2. The method for preparing a LDH intercalated composite graphene lubricant additive according to claim 1, characterized in that: The particle size D50 of the powdered graphene in step S1 is 3-6 μm, and the specific surface area is 750-850 m 2 / g.

3. The method for preparing a LDH intercalated composite graphene lubricant additive according to claim 1, characterized in that: The wet ball milling step in step S1 includes: placing 40 to 50 parts of commercially available graphene solution and 80 to 100 parts of deionized water in a stainless steel barrel of a ball mill, using a tetrafluoroethylene frosted dispersion disk, then adding zirconium beads into the barrel, connecting and turning on condensation water, controlling the ball mill speed to 4000 to 4400 r / min, stirring for 4 to 6 hours, and filtering to obtain a filtrate.

4. The method for preparing a LDH intercalated composite graphene lubricant additive according to claim 1, characterized in that: The conditions for vacuum freeze drying in step S1 include: vacuum degree of 10-12 Pa, temperature of -20--30° C., and time of 60-70 h.

5. The method for preparing a LDH intercalated composite graphene lubricant additive according to claim 1, characterized in that: The preparation method of the precursor in step S2 includes: dispersing 0.1 to 0.3 parts of the powdered graphene in 100 to 200 parts of deionized water to form a dispersion, dissolving 6 to 8 parts of zirconium oxychloride octahydrate and 0.6 to 0.8 parts of aluminum trichloride in 200 to 300 parts of deionized water to form a liquid A, dissolving 12 to 15 parts of an auxiliary agent in 250 to 300 parts of deionized water to form a liquid B, adding the liquid A and the liquid B to the dispersion for aging treatment to obtain a precursor.

6. The method for preparing a LDH intercalated composite graphene lubricant additive according to claim 5, characterized in that: The aging treatment conditions include: controlling the pH to 9.8-10.2, aging at room temperature for 12-14 hours, filtering, washing with deionized water, and vacuum drying.

7. The method for preparing a LDH intercalated composite graphene lubricant additive according to claim 5, characterized in that: The auxiliary agent is selected from one or more of sodium hydroxide, sodium carbonate, sodium bicarbonate and sodium phosphate.

8. The method for preparing a LDH intercalated composite graphene lubricant additive according to claim 7, characterized in that: The auxiliary agents are sodium hydroxide and sodium carbonate.

9. The method for preparing a LDH intercalated composite graphene lubricant additive according to claim 8, characterized in that: The mass ratio of sodium hydroxide to sodium carbonate in the auxiliary agent is (1.5-2.0):

1.

10. The method for preparing a LDH intercalated composite graphene lubricant additive according to claim 1, characterized in that: The intercalation modification step comprises: soaking the precursor in a 0.04-0.06 mol / L sodium laurate solution and stirring for 50-60 minutes, washing with deionized water, and drying.

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